When a significant weather event occurs, we often hear it being compared to “normal”. While this helps put an event into perspective, you may wonder – what is normal?
Climate normals, according to NOAA, are defined as the 30-year average at a given location. They are calculated for several climatological variables, including temperature and precipitation. Updated every decade, the current set of averages is based on the weather from 1981 through 2010.
These statistical measurements also help put climate trends into context. As greenhouse gas emissions continue to spew into the atmosphere, it should not come as a surprise that “normal” these days is warmer than it used to be. For the continental US, according to Climate Central, the average temperature has increased 1.4°F since 1980.
This may seem like a small number, but it is having big impacts. It reflects the increasing number of extremely hot days and the decrease in extremely cold days. Looking at daily temperature records across the US, record highs have outnumbered record lows in 26 of the last 30 years. In 2012, that ratio was as high as 7:1. These changes and the effects they have are what is meant by human caused climate change ushering in a “new normal”.